Setting aside the science-based rationale for sourcing flexible PVC replacement materials for medical devices, the commercial imperative for doing so is undeniable. Healthcare facilities around the world are reducing or phasing out the use of PVC and phthalates in medical devices: Kaiser Permanente, which spends $1 billion annually on medical supplies, no longer buys IV medical equipment made with PVC and DEHP-type plasticizers and, starting in July 2015, the use of tubes containing DEHP will be banned in French paediatric, neonatology, and maternity wards. Indications are that the ban may be extended to all medical devices used in French hospitals. Other examples abound. Consequently, industry has ramped up efforts to find alternative materials. A recent case in point is medical tubing extruder Microspec (Peterborough, NH), which has partnered with Styrolution (Frankfurt, Germany) to replace the PVC in its flexible multilumen tubing with a styrene-butadiene block copolymer (SBC).
The material offers better clarity than PVC, according to the companies, and features low drug absorption—a critical property since the tubing is used to administer medication. Ease of processing also was a primary factor for sourcing the material, says Microspec.
Sold under the Styroflex and Styrolux brand names, SBC materials from Styrolution met Microspec's stringent processability requirements for the extrusion of tubing with multiple lumens in varying shapes and diameters. Moreover, the materials provider had in-house expertise of the regulatory issues involved in the manufacture of medical devices.
"Styrolution offered Microspec a truly innovative solution that gave us the flexibility to not only create a more complex, multilumen structure for our product but also to meet industry medical tubing requirements to replace PVC and eliminate plasticizer migration," says Microspec manager Tim Steele. "The long-term formulations Styrolution offers through its HD Service Package was also a decisive factor for Microspec."
The HD service package offers fixed formulations and long-term notification of change, as well as extensive regulatory support.
Styroflex is an SBC with the properties of a thermoplastic elastomer suitable for extrusion, injection molding, and thermoforming. Characterized by a combination of high resilience and toughness, optical clarity and process stability, Styroflex offers good printability and adhesion to many different polymers. The material is also used as a high-performance additive to increase toughness and stress cracking resistance.
Styrolux resins are a range of thermoplastic SBCs that feature high transparency, brilliance, and impact resistance. Styrolux is miscible with polystyrene and allows toughness adjustments while reducing material costs, according to Styrolution. Styrolux can be extruded, thermoformed and injection molded.